Tmobile isn't wiping the floor with anyone. They are a company that is not concerned with their future as they have made it very clear they want to sell their assets to another company. It's a classic case of look good short term and sell high. They are in for a rude awakening as soon as their customers start defaulting on their payments with their no credit check installment options.

Sprint has already said their WiFi calling will require some sort of GPS fix first, either through Cellular or WiFi. Their app will actually check to ensure you're in the US before it'll allow you to make a call.

T-mobile's WiFi calling does work outside the US. I recently went on vacations to Punta Cana in Dominican Republic, and I was calling my family almost everyday to check on my son, using the resort's WiFi; and no extra charges when I received my bill the following month.

This isn't your traditional VOIP feature like Skype it is a third party app that allows you route your Sprint call to your WiFi network so you can have a better indoor signal in case you don't have one. Just like TMobile. Their WiFi calling with Tmo and Sprint isn't designed to give you FREE calling outside of network use. Outside of the USA you would be using another carriers towers which would require an additional charge as the service you are paying for is for domestic use.

If you travel often and don't want to get additional charges get SKYPE or buy a SIm in that country.

T-Mobile's wifi calling is free outside of the US too. When you're connected to wifi in the UK for example, your T-Mobile phone will behave as if it's connected to wifi in your house. Which means that calls to and from the US are no different when you're in the UK connected to wifi than they are when you're in your home connected to wifi. And if you were to try and call someone in the UK, it would cost exactly the same as it would if you were doing it from your house. So with T-Mobile's new plans, it would be more cost effective to connect to wifi when you want to call home, and disconnect if you need to call someone in the country you're visiting.

Article on the Sprint website tagged on this post here on phonescoop clearly states it will charge additional fees for Roaming outside the USA. This feature is intended to improve voice calls indoors where it can be degraded due to building materials and other factors. This is not mean to give you free calls in other countries. I am sure the Tmobile feature works the same way. Except with their recent plan change where they offer some included international services but not everywhere.

"Customer benefits include:

Enhanced coverage Easy setup: Once activated, everything is seamless and happens in the background Unlimited voice calling and messaging on Wi-Fi: All domestic calling and messaging is FREE (standard CDMA inte...(continues)

The feature isn't meant for Roaming outside of the USA is what I am clarifying for you.

Also "international calls" implies both calling form the USA to another country and trying to use the feature while traveling.

So that there is no confusion this features only purpose is to provide enhanced voice and text messaging coverage in areas inside the USA where you would otherwise have degraded service for w.e reason.

If you are Roaming outside the USA or Call another country your call is not free.

I can't see why folks are making such a big deal about this. just either get a cheap sim from the country you're in. Or get a free Google voice number and use it to make wifi calls. No need to even envolve a carrier into the picture. Or iPhone users could just use facetime audio to make calls. There's lots of free wifi calling options, that I can't even phathom why people are crying over sprint not allowing free international roaming.